Wireless telegraphy



Nov. 18, v 1,515,990

- R. D. BANGAY WIRELES S TELEGRAPHY Filed July 9, 1921 awbezutoz R. D.BANGAY Patented Nov. 18, 1924.

RAYMOND DORRINGTON BANGAY, OF LONDON, ENGLAND, ASSIGNOR TO RADIO COR-PORATION OF AMERICA, A CORORATION OF DELAWARE.

Application filed July 9, 1921.

Serial No. 483,566.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 11 STAT. 13,,1313.)

To all whom it may concern:

Be it known that I, RAYMOND Donnrns'ron BANGAY, a British subject, ofMarconi House, Strand, London, W. (3., England, have made certain newand useful Improvements in Wireless Telegraphy (for which I have filedan application in Great Britain November 16, 1915, Patent No. 16151 of1915), of which the following is a specifica tion.

In wireless telegraph transmitters it may. be advantageous or necessary,particularly with portable and aeroplane sets, to vary the length ofaerial used. In such cases de vices have to be provided for tuning theprimary and secondary circuits together and it is very desirable thatthese devices should occupy the minimum of space, give the maximum rangeof wave lengths and be easily and quickly operated. If, as is usual, theadjustment be made by varying part of the inductance in either circuit,the range of wave lengths is limited owing to the fact that part of theinductance is invariable; moreover, unless some further adjustment ismade, the coupling varies enormously with the wave length.

According to the present invention I employ in the primary circuit avariometer which constitutes as nearly as possible the whole inductanceof that circuit and at the same time forms the coupling with thesecondary circuit. Thus, if the aerial be lengthened causing an increaseof its wave length and a reduction of the coupling, the

' primary circuit is brought into tune by turning the movable coil ofthe variometer so as to increase the inductance of the circuit whichalso increases the coupling again. Therefore, with this single compactapparatus all the necessary adjustments for a wide range of wave lengthsmay be rapidly made by simply turning a handle.

The invention is illustrated by the accompanying diagrams.

In Figure 1, A is the moving coil and B is the fixed coil of avariometer included in the primary circuit; C is an inductance in theaerial circuit coupled to the coil A and B. If the length of the aerialis increased, the coil A is moved relatively to the coil B so as toincrease the total inductance of the primary circuit and this alsoincreases the coupling which was reduced by the lengthening of theaerial. If it be desired to vary the coupling without affecting thetuning, this may be done by moving the coil C relatively to the coils Aand B.

Figure 2 shows another method by which the coupling may be variedindependently of the primary circuit and without affecting the tuning.In this arrangement the aerial may be connected to various points of theinductance C, additional inductances C G which are not coupled to A andB and which are equal respectively to the portions of C which are cutout, being interposed between the aerial and the part of the inductanceC which remains in the aerial circuit, so that the total amount of theinductance (that is, C or part of G and C or a smaller part of C and Cremains constant though the part which is coupled to the primary circuitvaries.

Having described my invention, what I claim is:

1. A wireless telegraph transmitter adapted to operate with varyinglengths of aerial comprising a primary circuit having its inductance inthe form of a variometer, a coil in said aerial coupled to saidvariometer and means for varying the coupling between the coil andvariometer while maintaining the inductance constant.

2. A wireless telegraph transmitter adapted to operate with varyinglengths of aerial comprising a primary circuit having its inductance inthe form of a variometer having two relatively rotatable coils, a thirdcoil in the aerial inductively related to said variometer and means fordisconnecting turns of the aerial coil and substituting inductances ofsubstantially equal value noninductively disposed to said variometer.

RAYMOND DORRINGTON BANGAY.

